This invention relates to belt-type printing machines in which endless belts carry ordered sequences of printing plates for printing series of impressions in proper sequences on webs of sheet material such as paper.
Such machines are now well-established for effecting, for example, continuous printing of the individual pages of books, brochures and similar articles, said machines typically incorporating a pair of printing mechanisms each including an endless printing belt. Printing plates corresponding to the even-numbered pages of a book, brochure or the like to be printed are accurately located around one of said belts, while printing plates corresponding to the odd-numbered pages to be printed are accurately located around the other belt. The two belts are of identical length and are driven at the same speed, which speed is related to that of the web of sheet material, such that double-sided sheets to comprise the individual pages of the books, brochures or the like are accurately printed by the machine.
Such machines have proved extremely efficient in the production of printed articles comprising of the order of up to a few hundred individual pages.
When printing, for example, bingo tickets, it is often necessary to produce millions of such tickets all of which must be different. Even using the largest of the available belt-type printing machines, the time and cost involved is substantial. Further the initial artwork associated with the preparation of the individual millions of tickets involves extremely high costs.